Android NullPoinerException при показе объявлений AdMob

Question

У меня есть следующий код в моем приложении:

AdView ad; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    ad = new AdView(this); 
    ad.setAdSize(AdSize.SMART_BANNER); 
    ad.setAdUnitId("left out from question"); 
    RelativeLayout layout = (RelativeLayout)findViewById(R.id.layout); 
    layout.addView(ad); 
    AdRequest.Builder adRequestBuilder = new AdRequest.Builder(); 
    ad.loadAd(adRequestBuilder.build()); 
    setContentView(R.layout.activity_main); 

} 

И я получаю исключение нулевого указателя на строке, где я добавить мой AdView к моему Linear Layout. Что может быть здесь? Мой LogCat размещен ниже:

11-25 19:55:46.035: E/AndroidRuntime(346): FATAL EXCEPTION: main 
11-25 19:55:46.035: E/AndroidRuntime(346): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.adtest/com.example.adtest.MainActivity}: java.lang.NullPointerException 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.os.Looper.loop(Looper.java:123) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread.main(ActivityThread.java:4627) 
11-25 19:55:46.035: E/AndroidRuntime(346): at java.lang.reflect.Method.invokeNative(Native Method) 
11-25 19:55:46.035: E/AndroidRuntime(346): at java.lang.reflect.Method.invoke(Method.java:521) 
11-25 19:55:46.035: E/AndroidRuntime(346): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
11-25 19:55:46.035: E/AndroidRuntime(346): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
11-25 19:55:46.035: E/AndroidRuntime(346): at dalvik.system.NativeStart.main(Native Method) 
11-25 19:55:46.035: E/AndroidRuntime(346): Caused by: java.lang.NullPointerException 
11-25 19:55:46.035: E/AndroidRuntime(346): at com.example.adtest.MainActivity.onCreate(MainActivity.java:21) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
11-25 19:55:46.035: E/AndroidRuntime(346): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
11-25 19:55:46.035: E/AndroidRuntime(346): ... 11 more 

Answer 1

Попробуйте заменить

RelativeLayout layout = (RelativeLayout)findViewById(R.id.layout); 
layout.addView(ad); 
AdRequest.Builder adRequestBuilder = new AdRequest.Builder(); 
ad.loadAd(adRequestBuilder.build()); 
setContentView(R.layout.activity_main); 

с

setContentView(R.layout.activity_main); 
RelativeLayout layout = (RelativeLayout)findViewById(R.id.layout); 
layout.addView(ad); 
AdRequest.Builder adRequestBuilder = new AdRequest.Builder(); 
ad.loadAd(adRequestBuilder.build()); 

вы пытаетесь получить доступ к R.id.layout до того setContentView, что приведет к NullPointerException